Pathinettapadi (18 divine steps) to the sanctum sanctorium is divine in all aspects.
Every Ayyappa devotee, before he sees the Sanctum Sanctorum, has to lay his footsteps over eighteen sacred steps. Initially the 18 steps were made of granite. It was later covered with Panchaloha (a special composition of gold, silver, copper, iron and tin), in the year 1985 to prevent it from deterioration. Pilgrims initiate their ascent up the Pathinettam Padi by placing their right foot on the first step.
As per the tradition, only those who undertake the penance for 41 days and those who carry the irumudi on their head are allowed to use the steps.
The symbolism of these 18 steps is as follows:
The first five steps symbolise the five human senses (Panchendriyas) i.e. visual (vision), auditory (hearing), olfactory (smell), gustatory (taste) and tactile (touch). These signify the `mortal’ nature of one’s body. The next eight steps symbolise the eight Ashtaragas viz, Kama, Krodha, Lobha, Moha, Madha, Maltsarya, Asooya, Dhumb (Love, Anger, Avarice, Lust, Pride, Unhealthy Competition, Jealousy and Boastfulness). The next three steps stand for three Gunas or Thrigunas (nature-born qualities) i.e. Satva, ( perspicuity, discernment) , Rajas (activity, enjoyment) and Thamas (inactivity, stupor). The last two steps represent Vidya (Knowledge) and Avidya (Ignorance).
It is assumed that after climbing up these eighteen steps reverently, one symbolically detaches oneself from all the worldly ties that bind one physically and mentally to the world. It is only then that a person will be in a receptive condition to be ‘one’ in consonance with the concept of ‘The Ultimate Creator’.
The above is the most prevalent and accepted version of the significance of the Holy 18 steps.
(Source: http://www.ayyappaseva.org/blog )